Synopsis: Spotting Dark Matter with Supermaterials

Dark matter searches repeatedly draw a blank. One possible reason for the failure may be dark matter’s mass: Despite increased sensitivity, current detectors cannot spot the particles that make up this elusive matter if the particles are extremely light. Now Kathryn Zurek from the Lawrence Berkeley National Laboratory, California, and colleagues have come up with two new ideas for making detectors that should be capable of spotting such superlight particles.

In broad strokes, dark matter detectors are designed to operate as follows: Incoming dark matter particles strike the detector, gently nudging nearby atomic nuclei or electrons in the material from which the detector is made. These rare nudges generate small amounts of energy in the form of light or heat, which the detector registers. But the ability to detect particles of a certain mass depends on the properties of the detector material, such as the mass of its nuclei. Current detectors, made from semiconducting materials or liquid xenon, are sensitive only to particles heavier than about 10 million electronvolts.

Zurek and colleagues propose making detectors from superconducting aluminum or from superfluid helium instead. In the first case, the dark matter particles would interact with electron pairs in the superconductor and split the electrons apart. In the second, the particles would scatter from superfluid-helium nuclei and the nuclei would undergo multiple kicks. Both processes should produce an observable signal for particles as light as approximately 1 keV.